Manufacture of caps for armor-piercing projectiles.



UNITED STATES PATENT OFFICE.

ROBERT ABBOTT HADFIELD, OF SHEFFIELD, ENGLAND.

MANUFACTURE OF CAPS FOR ARMOR-PIERCING PROJECTILES.

Specification of Letters Patent.

Patented Nov. 28, 1905.

Application filed March 1, 1905. Serial No. 247,995.

To aZZ whom it may concern.-

Be it known that I, RoBERT ABBOTT HAD- FIELD, a subject of the King of Great Britain, and a resident of Sheflield, county of York, England, have invented an Improvement in the Manufacture of Caps for Armor-Piercing Projectiles, of which the following description is a specification.

This invention relates to caps for armorpiercing projectiles; and it has for its object the treatment of such caps whereby the efficiency of projectiles provided therewith is Very materially increased.

Caps for projectiles are usually made of mild steel, which as the result of very careful tests and experiments I find possesses very irregular qualities, for while showing excellent elongation in the ordinary tensile test it is really comparatively brittle under a sudden impact test, which is the character of test to which the cap is subjected in actual use. This is a matter of great moment, for if the cap gives way or becomes detached from the projectile at too early a stage in the impact of the projectile against a plate the projectile may fail through no fault of its own, but because of a fault inherent in the cap. In order to obviate such a disadvantageous and objectionable result, I have invented a novel and effective treatment for the wrought-iron or mild steel of which the cap is made. 7

The cap metal in accordance with my invention is heated to between 950 and 1,100 centigrade, according to the character of the iron or steel and the results desired, and then cooled in air or other cooling medium. I prefer, however, a quick cooling, as by quenching in water or other liquid, after which cooling the metal is reheated to a temperature of between about 600 and 800 centigrade, according to the toughness desired, and cooled slowly. By such treatment an exceedinglytough metal is obtained peculiarly suitable for caps for projectiles.

The described heat treatment may be applied to wrought-iron or mild-steel bars out of which the caps are to be machined, to caps after forging or machining to shape, either or both, or the caps may be cast to shape of mild steel and subjected to the specified heat treatment for toughening.

In order to avoid the difliculty of forging caps approximately to shape and the cost of subsequent machining to the requisite finished form, (thereby cheapening the man ufacture,) I may stamp the caps to the desired finished shape between suitable dies. Caps so made can then be subjected to the treatment hereinbefore described to toughen them.

Having fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In the manufacture of wrought-iron or mild-steel caps for projectiles, heating the metal-to a temperature of between 950 centigrade and 1,100 centigrade; quickly cooling the metal; reheating to a temperature of between 600 centigrade and 800 centigrade, according to the degree of toughness desired, and finally slowly cooling.

' 2. In the manufacture of wrought-iron or mild-steel" caps for projectiles, heating the metal to a temperature of between 950 centigrade and 1,100 centigrade; quickly cooling the metal by quenching in a liquid; reheating to a temperature of between 600 centigrade and 800 centigrade, according to the desired degree of toughness, and finally cooling slowly.

3. In the manufacture of wrought-iron or mild-steel caps for projectiles, heating the wrought-iron or mild steel to a temperature of about 1,100 centigrade; cooling quickly by quenching; reheating to a temperature above 600 centigrade and not higher than about 800 centigrade, and cooling slowly.

4. In the manufacture of Wrought-iron and mild-steel caps for projectiles, toughening the same by heating the metal to about 1,100 centigrade; cooling quickly; reheating to a temperature not higher than 800 centigrade, and finally cooling slowly.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ROBERT ABBOTT HADFIELD.

Witnesses:

G. H. HEMsoLL, ERNEST RODGERS. 

